PROJECT SUMMARY/ABSTRACT Children and adolescents are highly vulnerable to cardiometabolic adverse effects of antipsychotic treatment, which progress rapidly after medication initiation. Antipsychotic adverse cardiometabolic effects contribute to concerning pediatric health problems, adult morbidity, and shortened life span. Given the high rates of pediatric antipsychotic prescribing, public health strategies to improve child and adolescent cardiometabolic health outcomes must be portable for widespread dissemination and effective at engaging families early in antipsychotic treatment. The proposed application responds to NIMH's call for a population health approach to improve cardiometabolic health for youth with serious mental illness. The proposed intervention will be offered to a statewide population of Medicaid-insured, antipsychotic treated children and adolescents through a medication preauthorization program. Participants (8-16 years old) will be identified at the time of medication approval, and parent-youth dyads will be enrolled. The proposed study is a randomized trial of healthy lifestyle education (HLE) versus HLE plus two pediatric evidence-based strategies (reduce sugar sweetened beverage consumption through water delivery, increase physical activity through pedometer goal setting/tracking) for youth with serious mental illness who live in low-income families. We eliminate practical barriers to participation by providing an exclusively home-based intervention, and we address complex needs of families by integrating a telephone-delivered parent peer support (Family Navigator) throughout the intervention. Family Navigators are parents with the ?lived experience? of raising a child with serious mental illness. They can support other families by providing emotional support, resource information to address housing/food service needs, and practical/motivational support to implement family lifestyle changes. The intervention seeks to reduce disparities in cardiometabolic health by focusing the intervention solely on low-income families, but the approach is highly amenable to dissemination in other populations (e.g. private insured youth). The use of a well-trained lay professional workforce (Family Navigators) eliminates health system barriers, such as clinical provider shortages in underserved communities, as well as barriers to family engagement for overwhelmed and highly stressed parents. Comprehensive cardiometabolic assessments will be completed using methodologies consistent with the National Health and Nutrition Examination Survey to evaluate diet/activity outcomes. The study team brings together cardiometabolic and mental health experts to address the needs of a highly vulnerable population.